jointypes

Joint types are classifications of the mechanical connections that link components and constrain relative motion. They determine the degrees of freedom between joined parts and are foundational to the kinematic analysis of machines, robots, and structures. By choosing appropriate joint types, designers control motion range, stiffness, and load distribution.

Common joint types include revolute joints, which provide one rotational degree of freedom about a fixed axis (a hinge); prismatic joints, which provide one translational degree of freedom along a straight line (a slider); cylindrical joints, which combine rotation about and translation along the same axis; spherical joints, also known as ball-and-socket joints, that allow three rotational degrees of freedom; planar joints, which constrain motion to a plane (typically two translations and one rotation); universal joints, which connect two shafts at an angle and allow two perpendicular rotational axes; and screw joints, where linear translation is coupled to rotation by a helical constraint. Each joint type may be actuated or passive and may include limits, backlash, and compliance.

In robotics and mechanism design, joints are categorized as actuated or passive and form the basic building blocks of kinematic chains. The selected sequence and types of joints determine the reachable workspace, precision, speed, and control requirements of an arm, gripper, or machine tool. In computer-aided design and simulation, joint models feed into kinematic analyses such as forward and inverse kinematics.

Design considerations include load capacity, friction and wear, backlash, lubrication, manufacturing tolerances, and maintenance. Joints may also incorporate limits and compliance features. Understanding joint types supports effective design, analysis, and control across mechanical systems.